The speed of data communications networks has been increasing steadily and substantially over the past several decades, requiring newly designed components to enable the networks to operate at these new higher speeds. As the speed of networks increase, the frequency at which electrical signals in these networks are communicated increases, and physical wiring paths within the networks, which presented no problems at lower frequencies, can effectively become antennae that broadcast and receive electromagnetic radiation and cause errors in the data being communicated. This unwanted coupling of signals from one communication path or channel in a network to another channel, or among signal paths within a given channel, is known as “crosstalk” and degrades the overall performance of the network. Unwanted crosstalk can occur between any proximate electrically conductive paths that physically form parts of the network such as cables that carry the data signals and even within connectors used to connect cables to desired electronic components such as routers and network switches.
FIG. 1 is a diagram illustrating a portion of a conventional communications network 100 including a typical communications channel 101. The channel 101 includes a communications jack or outlet 102 into which a communications plug 104 of a cable 106 is inserted to thereby connect a computer system 108 to the communications network 100. The communications outlet 102 fits within an opening 110 of a wall plate 112 to expose an aperture 114 in the communications outlet into which the plug 104 is inserted. Electrical signals are then communicated to and from the computer system 108 through the cable 106, plug 104, outlet 102, and a cable 116. The cable 116 includes another communications outlet 118 on the other end of the cable, with this communications outlet which is often part of another network component such as a patch panel 120. A network switch 122 or other network component is connected to the outlet 118 through a cable 124 and plug 126 and interconnects the communications channel 101 to other components (not shown) within the network 100. The network 100 may, of course, include a large number of communications channels 101, as will be appreciated by those skilled in the art.
The cables 106 and 116, plugs 104 and 126, and outlets 102 and 118 are standardized components that include specified numbers of conductors and provide compatibility of new components, such as a new computer system 108, with the network 100. Standards organizations specify performance standards by which the outlet 102 and other components are categorized. Outlets meeting categories CAT6 and CAT6A performance standards, for example, must be capable of carrying signals in the 1 to 250 MHz and 1 to 500 MHz, respectively, frequency range. Unfortunately, typical outlets 102, 118 and plugs 104, 126 include up to eight wires or conductors, such as in RJ-45 outlets and plugs, that are spaced closely together within the outlets and plugs. This is illustrated in FIG. 2 which is a more detailed perspective view of the communications outlet 102 of FIG. 1. The outlet 102 includes an insulating housing or body 200 and a plurality of resilient conductive outlet tines T in parallel arrangement within an interior receptacle 202 of the body. The receptacle 202 is formed in a front 204 of the body 200 and the outlet tines T within the receptacle are connected to insulation displacement connectors (IDCs) 206 (not shown) situated within termination block 210 at a back 208 of the body. Wires within the cable 116 of communications channel 101 (FIG. 1) are then connected to the IDCs 206.
FIG. 3 is a perspective view of the communications outlet 102 of FIG. 2 with the body 200 removed to better illustrate the resilient conductive outlet tines T and other components within the outlet. The outlet 102 includes a printed circuit board 300 positioned near the back 208 of the outlet. The IDCs 206 are attached to the printed circuit board 300 and each of the tines T includes a fixed end 302 that is also attached to the printed circuit board. Conductive traces 304 on the printed circuit board 300, only one of which is shown to simplify the figure, interconnect the IDCs 206 and fixed ends 302 of the tines T. The tines T include free ends 306 positioned proximate the front 204 of the outlet 102. The outlet 102 further includes nonconductive and resilient spring arms 308 that function to support the tines T.
Due to the close spacing of the tines T within the outlet 102, the frequency of signals being communicated increases in high speed networks such as 10 Gigabit or “10 G” networks like 10 G Ethernet networks (10 GigE). In these networks, increased crosstalk can occur among the tines T within the outlet 102 and among corresponding tines (not shown) within the plugs 104, 126 (FIG. 1). FIG. 4 is a schematic of the outlet 102 of FIGS. 1-3 and illustrates eight conductors C1-C8 contained in the outlet. Each of the eight conductors C1-C8 represents the corresponding conductive outlet tine T, conductive traces 304 on the rigid printed circuit board 300, and IDC 206. Thus, in FIG. 4 portions of the conductors C1-C8 on the left side of the figure correspond to the outlet tines T in the outlet 102 (FIG. 3) that extend from the free ends 306 of outlet tines T to the fixed ends 302 of outlet tines T (FIG. 3). The portion of conductors C1-C8 on the right side represent the conductive traces 304 and IDCs 206 that are situated at the back 208 (FIG. 3) of the outlet 102.
The eight conductors C1-C8 form four signal pairs P1-P4, with conductors C4 and C5 being pair P1, conductors C1 and C2 being pair P2, conductors C7 and C8 being pair P4, and conductors C3 and C6 being pair P3. Each pair P1-P4 of conductors C1-C8 carries a corresponding electrical signal, as will be appreciated by those skilled in the art.
As shown in FIG. 4, the conductors C1 and C2 of pair P2, C4 and C5 of pair P1, and conductors C7 and C8 of pair P4 “crossover” towards the front 204 to reduce internal crosstalk within the outlet 102. These crossovers help reduce internal crosstalk among the pairs P1-P4 within an individual communications channel 101 (FIG. 1). The term “internal crosstalk” is used to mean crosstalk that occurs among the pairs P1-P4 of conductors C1-C8 within an individual or single communications channel 101 (FIG. 1). Internal crosstalk is thus the unwanted effect of a signal being communicated on one conductor C or pair P on the signals being communicated on another conductor C or pair P within the outlet 102. The fact that such internal crosstalk presents problems at higher frequencies is well known to those skilled in the art. In particular, the close spacing of conductive plates and conductor routing within plug 104 (FIG. 1), the close spacing of the outlet tines T and the asymmetrical electrical exposure of conductors C3 and C6 of pair P3 to the conductors of pairs P1, P2, P4 are all significant causes of increased internal crosstalk at the higher frequencies of transmission required for current communications outlets. For example, conductors C7 and C8 of pair P4 are affected more by the signal on the conductor C6 due to the small physical separation between these conductors. Conversely, conductors C1 and C2 of pair P2 are affected more by the signal on the conductor C3, once again due to the small physical separation between these conductors. Due to the separation or “splitting” of the conductors C3 and C6 of pair P3, this pair of conductors is commonly referred to as the “split pair.” The split pair configuration of P3 is historical and current outlets maintain this configuration for compatibility reasons.
There is a need for an improved communications outlet having reduced susceptibility to internal crosstalk without significantly increasing the expense and the complexity of manufacturing the outlet.